Field of the Invention
This invention relates to a hydrostatic traction drive system of a mobile machine with a first hydraulic traction motor associated with a first vehicle side and a second hydraulic traction motor associated with a second vehicle side. The two traction motors are each operated in an open circuit and are jointly supplied with hydraulic fluid by a single hydraulic pump. The first traction motor can be controlled by a first control valve and the section traction motor can be controlled by a second control valve.
Description of Related Art
Hydrostatic traction drive systems on mobile machines in which a hydraulic traction motor is associated with each vehicle side are referred to as bilateral traction drive systems. Bilateral traction drive systems make it possible to steer the mobile machine by differential steering. Traction drive systems of this type are used, for example, on mobile machines in the form of tracked vehicles, such as excavators, tracked bulldozers, or tracked loaders, wherein the traction motors drive corresponding caterpillar treads or tracks.
DE 43 03 243 C2 describes a bilateral hydrostatic traction drive system for a mobile machine in which the two hydraulic traction motors are each operated in a closed circuit and a first hydraulic pump is provided for the supply of the first hydraulic traction motor and a second hydraulic pump is provided for the supply of the second hydraulic traction motor. Bilateral hydrostatic traction drive systems in which a separate hydraulic pump is associated with each hydraulic traction motor are termed dual circuit systems. Dual circuit systems offer energy-efficient performance when the mobile machine travels around a curve, although on account of the two hydraulic traction pumps the effort and expense of construction are high.
The effort and expense involved in the construction of bilateral hydrostatic traction drive systems can be reduced by the use of a single-circuit system, in which the two hydraulic traction motors are each operated in an open circuit and a single hydraulic pump is used to supply the two hydraulic traction motors. When the mobile machine comprising a bilateral hydrostatic traction drive system having a single-circuit travels around a curve, however, high differential pressures can occur between the two traction motors and as a result high power losses can occur.